Do some people always survive catastrophes?
Yes, some people always survive catastrophes. Regardless of the catastrophe, there are always survivors, as illustrated by a woman who survived Hiroshima under ground zero and survivors pulled from the collapsed San Francisco freeway after the earthquake. This pattern also applies to the end of the tribulation.
Les teaches that no matter what kind of catastrophe people endure, there are always some survivors. He illustrates this with the Hiroshima bombing, where a woman right under ground zero survived because the books in the library buried her, and the paper insulated her from the heat flash and radioactivity; she was totally burned but survived. He also points to the San Francisco earthquake, where workers lifting heavy concrete from the collapsed freeway found survivors. Les applies this to the end of the tribulation, when survivors will be scattered around the planet from every nation. He then has his class estimate what "a few" means, rounding the world population to five billion and suggesting less than five percent.